The effect of riparian condition on invertebrate drift in mountain streams     

Shelley E. R. Hoover  Leanne G. W. Shannon  Josef Daniel Ackerman 《Aquatic Sciences - Research Across Boundaries》2007,69(4):544-553

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Small pelagics in upwelling systems: patterns of interaction and structural changes in "wasp-waist" ecosystems     

Cury  Philippe; Bakun  Andrew; Crawford  Robert J. M.; Jarre  Astrid; Quinones  Renato A.; Shannon  Lynne J.; Verheye  Hans M. 《ICES Journal of Marine Science》2000,57(3):603-618

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Latest Pleistocene and Holocene glacial events in the Colonia valley,Northern Patagonia Icefield,southern Chile          下载免费PDF全文

David A. Nimick  Daniel McGrath  Shannon A. Mahan  Beverly A. Friesen  Jonathan Leidich 《第四纪科学杂志》2016,31(6):551-564

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The remarkable occurrence of large rainfall-induced debris flows at two different locations on July 12, 2008, Southern Sierra Nevada, CA, USA     

Jerome V. DeGraff  David L. Wagner  Alan J. Gallegos  Margie DeRose  Casey Shannon  Todd Ellsworth 《Landslides》2011,8(3):343-353

On July 12, 2008, two convective cells about 155 km apart produced a brief period of intense rainfall triggering large debris flows in the southern Sierra Nevada. The northernmost cell was centered over Oak Creek Canyon, an east-flowing drainage, and its tributaries near Independence, CA, USA. About 5:00 p.m., debris flows passed down the South Fork and North Fork of Oak Creek to merge into a large single feature whose passage affected the historic Mt. Whitney Fish hatchery and blocked California State Highway 395. At about the same time, the southernmost cell was largely centered over Erskine Creek, a main tributary of the west-flowing Kern River. Debris flows issued from several branches to coalesce into a large debris flow that passed along Erskine Creek, through the town of Lake Isabella, CA, USA and into the Kern River. It was observed reaching Lake Isabella about 6:30 p.m. Both debris flows caused significant disruption and damage to local communities.  相似文献   

Meat consumption and climate change: the role of non-governmental organizations     

Linnea I. Laestadius  Roni A. Neff  Colleen L. Barry  Shannon Frattaroli 《Climatic change》2013,120(1-2):25-38

The contribution of livestock production to climate change is now widely acknowledged. Despite this, efforts to reduce meat consumption in light of climate change have been relatively limited. One potential avenue for encouraging consumption changes is via non-governmental organizations (NGOs). This study used a qualitative approach to understand how and to what extent environmental, food-focused, and animal protection NGOs in the U.S., Canada, and Sweden have worked to reduce or alter domestic meat consumption in light of climate change. While almost all of the NGOs examined had mentioned the issue on their websites, few had established formal campaigns to reduce meat consumption. Active public outreach was dominated by animal protection and food-focused groups, particularly in the U.S. and Canada. Animal protection organizations advocated for larger reductions in meat consumption than environmental groups. Few NGOs sought to promote national-level polices to reduce meat consumption. There is a continued need for public education campaigns with clear messages, particularly by environmental NGOs, as well as efforts to build support for policy measures that seek to reduce meat consumption.  相似文献   

Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) Dopplergrams     

Peter E. Williams  W. Dean Pesnell  John G. Beck  Shannon Lee 《Solar physics》2014,289(1):11-25

Co-temporal Doppler images from Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) have been analyzed to extract quantitative information about global properties of the spatial and temporal characteristics of solar supergranulation. Preliminary comparisons show that supergranules appear to be smaller and have stronger horizontal velocity flows within HMI data than was measured with MDI. There appears to be no difference in their evolutionary timescales. Supergranule sizes and velocities were analyzed over a ten-day time period at a 15-minute cadence. While the averages of the time-series retain the aforementioned differences, fluctuations of these parameters first observed in MDI data were seen in both MDI and HMI time-series, exhibiting a strong cross-correlation. This verifies that these fluctuations are not instrumental, but are solar in origin. The observed discrepancies between the averaged values from the two sets of data are a consequence of instrument resolution. The lower spatial resolution of MDI results in larger observed structures with lower velocities than is seen in HMI. While these results offer a further constraint on the physical nature of supergranules, they also provide a level of calibration between the two instruments.  相似文献   

The critical inclination in artificial satellite theory   总被引：1，自引：0，他引：1  

Shannon L. Coffey  André Deprit  Bruce R. Miller 《Celestial Mechanics and Dynamical Astronomy》1986,39(4):365-406

Certain it is that the critical inclination in the main problem of artificial satellite theory is an intrinsic singularity. Its significance stems from two geometric events in the reduced phase space on the manifolds of constant polar angular momentum and constant Delaunay action. In the neighborhood of the critical inclination, along the family of circular orbits, there appear two Hopf bifurcations, to each of which there converge two families of orbits with stationary perigees. On the stretch between the bifurcations, the circular orbits in the planes at critical inclinmation are unstable. A global analysis of the double forking is made possible by the realization that the reduced phase space consists of bundles of two-dimensional spheres. Extensive numerical integrations illustrate the transitions in the phase flow on the spheres as the system passes through the bifurcations.A delicacy so very susceptible of offence...—Hester Lynch PIOZZI,Observations and Reflections made in the Course of a Journey through France, Italy and Germany (1789)NAS/NRC Postgraduate Research Associate in 1984–1985.  相似文献   

The editor's half‐page     

Shannon McOune 《The Professional geographer》2013,65(4)

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The Southern Ontario All-sky Meteor Camera Network     

R. J. Weryk  P. G. Brown  A. Domokos  W. N. Edwards  Z. Krzeminski  S. H. Nudds  D. L. Welch 《Earth, Moon, and Planets》2008,102(1-4):241-246

We have developed an automated network of all-sky CCD video systems to detect medium–large meteoroids ablating over Southern Ontario, Canada. The system currently consists of five stations with the largest baseline being 180 km. Each site runs a video rate recorder with sufficient resolution to determine meteoroid trajectories with a typical precision of about 300 m but no worse than 1 km. The sensitivity of the camera is close to a stellar visual magnitude of +1 which allows for astrometric calibrations using field stars. Photometric procedures have also been developed and tested. The system has a limiting magnitude for meteors of about −2 with the current detection algorithm.  相似文献   

Assessment of the UV camera sulfur dioxide retrieval for point source plumes     

Marika P. Dalton  I. Matthew Watson  Patricia A. Nadeau  Cynthia Werner  William Morrow  Jeremy M. Shannon 《Journal of Volcanology and Geothermal Research》2009

Digital cameras, sensitive to specific regions of the ultra-violet (UV) spectrum, have been employed for quantifying sulfur dioxide (SO₂) emissions in recent years. The instruments make use of the selective absorption of UV light by SO₂ molecules to determine pathlength concentration. Many monitoring advantages are gained by using this technique, but the accuracy and limitations have not been thoroughly investigated. The effect of some user-controlled parameters, including image exposure duration, the diameter of the lens aperture, the frequency of calibration cell imaging, and the use of the single or paired bandpass filters, have not yet been addressed. In order to clarify methodological consequences and quantify accuracy, laboratory and field experiments were conducted. Images were collected of calibration cells under varying observational conditions, and our conclusions provide guidance for enhanced image collection. Results indicate that the calibration cell response is reliably linear below 1500 ppm m, but that the response is significantly affected by changing light conditions. Exposure durations that produced maximum image digital numbers above 32 500 counts can reduce noise in plume images. Sulfur dioxide retrieval results from a coal-fired power plant plume were compared to direct sampling measurements and the results indicate that the accuracy of the UV camera retrieval method is within the range of current spectrometric methods.  相似文献